text: Monika Suchanek, Anna Radzikowska and Christoph Thiele carried out an experiment in which they had successfully managed to label proteins from the cells of a monkey's kidney (COS7).
  These cells were grown in a high-glucose medium, from which a sample of 3 cm² was removed to proceed with the western blotting. At about 70% of confluence, the initial medium was replaced by another one lacking the amino acids methionine, leucine, isoleucine and valine, as well as phenol red.
  Afterwards, photo-amino acids were added to a final concentration of 4 mM of photo-leucine and photo-isoleucine, 1.7 mM of photo-methionine, and cultivated for 22 hours. Once the time was over, cells were washed using PBS and UV-irradiated using a 200-W high pressure mercury lamp with a glass filter that removed wavelengths under 310 nm during 1 to 3 minutes. This did not affect to the viability of the cell (which only was altered after 10 minutes of irradiation). Cell was driven to lysis and subsequent western blotting to analyse the isolated cross-linked complexes.
  MacKinnon A. L. et al. used photo-leucine to label proteins in a crude membrane fraction, which allowed them to identify the central part of a translocation channel within the membrane that is the target of the cyclodepsipeptide inhibitor.